Heating Operation; Space Temperature Setpoint Arbitration - Trane Tracer AH540 Setup And Operation

Chapter 4 Sequence of operation
36

Heating operation

In the heating mode, the Tracer AH540/541 controller attempts to main-
tain the space temperature at the active heating setpoint. Based on the
controller occupancy mode, the active space heating setpoint is one of the
following:
Occupied heating setpoint
•
Occupied standby heating setpoint
•
Unoccupied heating setpoint
•
The outputs are controlled based on the unit configuration and the
required machine heating capacity. At 0% machine heating capacity, the
heating capacity is at its minimum position. As the required machine
heating capacity increases, the heating capacity is opened above its mini-
mum position. At 100% machine heating capacity, the heating capacity is
open to its maximum position.
The economizer outdoor air damper is never used as a source of heating.
The economizer damper is used only for ventilation when the unit is heat-
ing. For more information, see "Outdoor air damper operation" on
page 56.

Space temperature setpoint arbitration

The space temperature setpoint can be communicated either by a build-
ing automation system or peer-to-peer using a binding (see "Communica-
tion with other controllers" on page 3). When the Tracer AH540/541 is in
occupied mode, occupied standby mode, or occupied bypass mode, a com-
municated setpoint takes precedence over a local (hard-wired) setpoint.
When neither a communicated nor a local (hard-wired) setpoint is
present, the controller uses the locally stored default heating and cooling
setpoints.
The exception is when the controller is in unoccupied mode. Then the con-
troller always uses locally stored default unoccupied setpoints. These set-
points are configured at the factory prior to shipment. Use the Rover
service tool to modify these default unoccupied setpoints.
Zone sensor setpoint thumbwheel
Zone sensors with an internal or external setpoint thumbwheel (1 kΩ)
provide the Tracer AH540/541 controller with a local setpoint (50ºF to
85ºF [10ºC to 29.4ºC]). An internal setpoint thumbwheel is concealed
under the front cover of the zone sensor. To access it, remove the zone sen-
sor cover. An external setpoint thumbwheel (when present) is accessible
from the front cover of the zone sensor.
When the local (hard-wired) setpoint thumbwheel is used to determine
the setpoints, all unit setpoints are calculated based on the local setpoint
value, the configured setpoints, and the active mode of the controller.
CNT-SVX05B-EN